What a joy it is to chronograph these little rifles instead of the 12gaFH 3.85" Shotgun Slugger!

How about an 8,033 ft-lbs KE varmint and deer bullet?
Four Foot-Tons for plains game?
OK for lion and cape buffalo at that rate with the GSC HV 50-cal-450-grainer?
Needs testing!

Quality Cartridge brass of 2.940" length: 152.7 grains of water gross
If it ever grows to 3.000" max length: 155.8 grains H2O

It is bigger than a 500A2, hence will need more powder to get more velocity at the same pressure, or same velocity at lesser pressure.

The bullet types used:



Top to bottom, above, three bullets:

1. 450-grain GSC HV was .512" and had the bands sized to .510" before loading.
This bullet was most accurate.
It also gave (+)126 fps higher velocity than predicted by QL, with no signs of excess pressure.


2. 570-grain Barnes TSX was .508" diameter.
It gave less velocity than predicted by QL: (-) 86 fps.
Of course, QL thought it was a .510" bullet, and QL did not know it would be letting gas blow by in the rifling grooves.
However that gas blew by consistently, and there was a velocity extreme spread of only 18 fps for 6 shots.
Groups larger than GSC.

3. 777-grain FNGC NEI cast boolit with Hornady 50-cal gas check and LBT Blue Lube, was .513" diameter in a Lyman No.2 alloy equivalent, before it was sized to .510".
It gave (-) 68 fps less velocity than QL predicted, but had an extreme spread of only 25 fps for 6 shots.
Groups larger than GSC.
Not bad for my first try with this cast boolit.

The loads, Quality Cartridge brass, GM215M primer:



450-grain HV with 115.0 grains of Hodgdon Benchmark Extreme:
QL predicted: 2709 fps ... 58,576 psi
Actual: 2835 fps

570-grain TSX with 105.0 grains of Hodgdon Varget Extreme:
QL predicted: 2384 fps ... 58,641 psi
Actual: 2298 fps

777-grain FNGC with 100.0 grains of Hodgdon H4831SC Extreme:
QL predicted: 1828 fps ... 38,904 psi
Actual: 1760 fps

The chronograph was at 15 feet from muzzle. No correction for that 5 yards was made to the above actual velocity averages.

GSC 50-yard accuracy over the chronograph with 2.5X Leupold:
This load is faster than I want, and there was about 5% air in the load, seemed more like a 95% fill, less than the 98% fill that QL predicted.
Benchmark is a fast powder, just a bit slower than IMR-3031.
I still think in terms of the IMR powders I started reloading with, but am now a Hodgdon Extreme devotee.
I will reduce the load and add Dacron filler packed tight and get the accuracy better.
The first three shots were used to zero on another target, after bore sighting by peeping through the bore at the range, then one-shot groups times 3, with windage and elevation adjustments times three, after each single shot.
Voila! Shots 4,5,6 grouped like this:



Fired brass:





Rifle has 25" barrel, 1:10" twist, stainless McGowen, on a CZ action, laminate stock, VAIS Brake.
This shopmule is sweet, but I need a fancier 500 Mbogo of lighter weight.

6 shots of each of those three loads was all I tried today.
Kids! Don't try that at home!

I will back down on the powder charge for 450-grainer load and add filler, or maybe just add filler.

Go up on the 570-grainer load: GSC FN is the only decent 570-grainer I know of, other than Woodleighs, which handle up to 2200 fps impact for the 500 NE.
The old 570-grain XLC from Barnes was about .509" instead of .508", and worked O.K. in the 500A2.

Woodleigh 600-grain PP-soft for the 500 jeffery handles up to 2250 fps impact. Hope they are .510".
That might do.

The 777-grainer is nice as it is.
Harder alloy and it will beat any 45-70 that ever walked the earth!

570 @ 2,300


That will Git-R-Done!

Let's see one loaded with a 647 API. Veolocity?

quote:

Originally posted by boom stick:
570 @ 2,300


That will Git-R-Done!

boom stick,
Congratulations! First to respond to the latest 500 Mbogo thread. Doing good ain't got no end ... it is its own reward. You're good!

But the 500A2 with 570-grain XLC's GSC FN's will do better than that ... The TSX is undersized and loses a lot of gas around the bullet. Not good.

Need better bullet than "50-cal" TSX.

Getting back into the middle-bore testing business RIP ..?? Has the Iron Buffalo gone totally feral or can it ne herded back to the ranch ...??

quote:

Originally posted by fla3006:
Let's see one loaded with a 647 API. Veolocity?

Those are best saved for black ops.
Would you settle for some standard ball of same weight? Will do that.

And besides, you know it ain't gonna be that much different from your .510 Wells, 500 A2, or 50 Peacekeeper.
Just more exotically delivered. No belt.

quote:

Originally posted by Macifej:
Getting back into the middle-bore testing business RIP ..?? Has the Iron Buffalo gone totally feral or can it ne herded back to the ranch ...??

Macifej,
I am stalled on the 12GaFH for now.
Back to the rarified air of the world's only 500 Mbogo. Like standing on top of Mount Everest, when you know you are so special.
.395 Tatanka gives me the same "shiver me timbers!"

Mbogo, Tatanka, Iron WaterBoard Buffalo ...
A lot of bull.
All still available for a roundup.

But everytime the IWBBuff gets trotted out of pasture, the BS gets piled up too deep to shovel ... Nonbelievers!

quote:

But everytime the IWBBuff gets trotted out of pasture, the BS gets piled up too deep to shovel ... Nonbelievers!

True ... they don't see the value in relativity I guess ... it's your Ark - not every fish and fowl deserves a suite on the promenade deck.

Still doing load development.
Have some of Ye Olde Barnes Originals.
Thick copper jacket and soft lead core, 600-grainers that meausre .510".
Maybe H4895 for 2600 fps and work down from there?
Ah, the perfect "stopping rifle."
Will horde the 570-grain GSC FN's.
Those make it suitable for Texas Heart Shots on elephant.

How sweet it is, the match of 500 Mbogo Dave Manson reamer,
Quality Cartridge brass,
Redding dies,
and a flawlessly functional cartridge design underlying all of it:
Perfection.

I'm going squirrel hunting in a few hours.
Opening day of spring squirrel.
Mighty tasty.

There's a season for squirrel ... ??

The "season" back home was anytime it was too cold for the bugs and snakes and gators ...

Yes, there is a spring squirrel season.
It is for the birds!
I forgot my mosquito headnet and gloves.
I sprayed myself with deet but forgot the permethrin!
Deet does nothing to KY ticks, chiggers, and mosquitos!
I am still nursing my itchy wounds and didn't find one of those deer ticks until 48 hours after it arrived on my corpulence!
taking doxycycline now!
I was so busy shooing mosquitoes out of my ear holes and nostrils that I am sure I shooed every squirrel for miles!
I'll stick to fall and winter squirrel hunting and keep looking for trophies like GI Joe got, below.

My next 500 Mbogo barrel is on the way from Pac-Nor now, right on their estimated delivery of 8 weeks.
1:9" TWIST, No.6 sporter, stainless match/super, 8-groove, 28", to be cut ASAP.
That is a standard offering from Pac-Nor.

Is the 500 Mbogo case a necked up 416 Rigby case ?

First "Hogzilla" now Squirrelzilla"

quote:

Originally posted by RIP:
Yes, there is a spring squirrel season.
It is for the birds!
I forgot my mosquito headnet and gloves.
I sprayed myself with deet but forgot the permethrin!
Deet does nothing to KY ticks, chiggers, and mosquitos!
I am still nursing my itchy wounds and didn't find one of those deer ticks until 48 hours after it arrived on my corpulence!
taking doxycycline now!
I was so busy shooing mosquitoes out of my ear holes and nostrils that I am sure I shooed every squirrel for miles!
I'll stick to fall and winter squirrel hunting and keep looking for trophies like GI Joe got, below.

My next 500 Mbogo barrel is on the way from Pac-Nor now, right on their estimated delivery of 8 weeks.
1:9" TWIST, No.6 sporter, stainless match/super, 8-groove, 28", to be cut ASAP.
That is a standard offering from Pac-Nor.

quote:

Originally posted by gumboot458:
Is the 500 Mbogo case a necked up 416 Rigby case ?

gumboot458
The 500 Mbogo is a blown out and lengthened and necked up .416 Rigby, with 35-degree shoulder moved out farther from base, instead of the 45-degree Rigby.

So is the 470 Mbogo.

The 500 Mbogo is more precisely a further necked up and further lengthened 470 Mbogo.

The 500 Mbogo matches the 470 Mbogo all the way to where the neck starts on the 500 Mbogo.

Hopes are to fire the 2.940" 500 Mbogo brass until it grows to 3.000" max length.
Then it will be ready for scrap.
I will do my best to try to loosen the tight primer pockets.

The 500 Mbogo is about midway between the 500A2 and the 500 Jeffery in case capacity, depending on brass.

As secretive as the 500 Jeffery boys are about their 500 Jamison brass gross water capacity, I am wondering if the 500 Mbogo QualCart (Hornady) brass is bigger than the 500 Jeffery Jamison brass, internally.

Squirrelzilla!

Squizilla - diminutive form ...

RIP,

What is the availability of reamers and dies? I ask frankly because the A2 sucks!

.. RIP . Thanks for the info ..

Scott , your out to lunch .

gumboot458,
Excuse me?

quote:

Originally posted by ScottS:
RIP,

What is the availability of reamers and dies? I ask frankly because the A2 sucks!

ScottS,
I am sure you have seen the 500 Jeffery/.505 Gibbs thread by now. Info there.

RIP , anything new to report on the new 500 Mbogo ??? , Did there need much rail or ramp work from the 416 action to get it to feed well ??

gumboot458,
Kevin rebarreled a CZ 550 .416 Rigby for my shopmule last year.
I gave him some dummies for feed work, just the Barnes stuff, I did not include the GSC FN, nor make an issue of it feeding the FNs.
I just wanted a 500 Mbogo to do some shooting with, and a VAIS brake for load development.
I can tell he did some polishing on the rails and ramp.



All the spitzers and roundnose feed well.
It feeds the FN from the left side of the stack.
It balks on feeding the FN from the right side of the stack.

My Mauser 450 Dakota feeds the GSC FN from either side of the stack with ease, even with the 500 Mbogo dummies.



I think the 500 MbogoMobogo, which is a flawless cartridge, deserves a flawless feed job too.

Still working on that.

The CZ will not hold 4 down in 500 Mbogo, only 3 in the box, though a fourth can be fed off the top of the box CRF by thumbing down a 4th cartridge enough to get the rim to start into the boltface.

The SIGARMS Magnum Mauser gets 4 down in the box with 450 Dakota and even with 500 MbogoMobogo, but the shoulder rubs tight on the bolt when it closes on the 500 MbogoMobogo.
However, it will feed the fourth cartridge off the top of the box with ease, leaving room to spare for the three in the box, 500 MbogoMobogo.

Thinking of rebarreling the Magnum Mauser.
Gotta catch Kevin on his summer break from medical school ... will meet with him Saturday, six days hence.

That will be a quick rebarrel, and add the barrel accessories, including a barrel recoil lug, which the Mauser Masters left off in 450 Dakota.
If I leave it with a 25" barrel, like the original Mauser Banner rifle has,
The muzzle diameter will change from .670" in 450 Dakota,
to .770" in 500 MbogoMobogo.
Pac-Nor sporter No.6 stainless 1:9" twist.
Might weigh 9.75 to 10 pounds instead of the current 9.5 pounds.
Might correct the slightly butt-heavy balance of the 450 Dakota to perfection as a 500 Mbogo.
I also plan to have the 14.75" LOP over a .7" pad corrected to 14.50" over a 1" pad.

Proper engraving of the barrel will be required,
with reproduction of the Mauser banner and the serial number on the barrel.

That serial number is MM 00XX.
MM stands for
Magnum Mauser
and
MbogoMobogo.

This one feeds the FN 500 Mbogo dummies:



Kevin extensively reworked that BRNO ZKK 602 for the 500A2 equivalent .510/460Wby Improved Jenkins and Berry (JAB).
It has great personal-historical significance as is.
I hesitate to rebarrel it.

I really need a synthetic stock to fit a Magnum Mauser.

Then I could set aside the "pretty" stock and barrel of the 450 Dakota,
for later reassembly to original.

A flawless 500 MbogoMobogo will require a synthetic stock afterall.
Mere walnut will never do.

My lord man!!!!!!! If a T-Rex gets in your flower garden he has a surprise coming!!!!! That is impressive!! BTW what did that squirrel score B&C?

I forget the B&C numerical score on that squirrel, but I think it was in the top three.

Thanks for the update . . I wonder why Mauser didn,t put a 2nd lug under the barrel ..With a stock that nice , ... For a shop mule the Mbogo is real nice ..

Unaware of the other .50s being thought up for the .416 Rigby case at the time this is actual chrono data and an email I sent out from 1999 and early 2000.

"You know paper ballistics are one thing, seeing the effects of it are another. Enjoy the rest of this

Most of you have known I am working on a new .505 based on the .416 Rigby case.

Days ago I finally chrono'ed the first of a group of semi production rifles Mike Kisler and I have been working on.

While I have load data from a 525 gr lead bullet @ 1850FPS all the way up to a 600gr Woodliegh @ 2500fps, those are the extremes.

I designed the round to be one of the more efficient big bore available. The loads I wanted were a 525gr. @ 2300fps and a 600gr @ 2200fps. I am close. Just over 6500 ft# of energy on either load as tested. I wanted to better the
.500 Jefferies and the .500 Nitro and keep pressure down. Easy enough to do and with less recoil, if the .505 Gibbs is any comparison for either.

Info from a Pact chrono and A2 data:

From a 21.5" PacNor barrel and a 525gr Woodliegh soft I am getting an average of 2362fps with 100grs of H4895.
SD is 6.7,
CV .37%
MAD 8.8,
ES 25fps....in 20 rounds!!

From 96 grains of H4895 and a 600 grain Woodliegh soft...............2210fps average
SD is 9.8
CV .53% MAD 9.8
ES 23fps......in 20 rounds!

Recoil is less than a similar weight rifle chambered in .416 Rigby with 400 grain bullets at 2500FPS when compared to the .505 with 525 grains @ 2350fps."

Anyone ever pressure test these wild cats?

More here on the .505 version.

http://pistolsmith.blogspot.co...10/07/505-burns.html

Thanks to Dane Burns for goosing this thread out of the cemetery, it is undead, again!



His .505 Burns was done before the 500 Mbogo, jawohl!

Look closely here, at his .505 Burns, the two in the center, flanked by .416 Rigby on the left and .505 Gibbs on the right:

Yep, the 500 Mbogo shoulder is almost identical, 500 AR too, though done with .510-cals instead of .505-cal bullets.

RIP,

Those prints were revisions of the earlier 505 based on the Rigby case, so I have prints for a 505/416 and that print for a 505 based on 450 Dakota brass 505/450, that I found WAYYY...Way easier to work with.

Loved reading here the last couple of days the posts made 6 or 7 years after I was shooting my 505 saying a 50 cal 416 Rigby wildcat just could not be done because of head space

The funny thing is back in the day I use to read this forum ( I think but may be not) on occasion and loved reading Saeed's comments/hunts on other earlier forums as well.

I had no idea others were looking at the 500/416 idea. But with some searching here it is obvious...great minds think alike

Tells you what I think of wild cats based on on the Gibbs and belted cartridges in a DGR.

I had almost forgotten about my "baby" .505s till the author of "Safari Dreams", Kenneth Royce, who had mistakenly credited my original work to Van Horn a few years back (which I never saw but customers did) asked me last week about the real story behind my .505. I really appreciate that he finally asked and wanted to set the record straight. .505 web page blog entry was the result and it also brought me here. Yahoo!

Any pressure testing? RIP, any way you can repost your test target photos?

Just as much fun was seeing my personal 9.3x62 that I had to sell off after an injury that made it to Africa without me and took a buffalo among other nice trophies. That was pretty cool to see.

cheers,
Dane

Dane,
Yes, lots of naysayers around here have been converted, including me!
I actually thought John Buhmiller beat you to the "500" on the .416 Rigby case, by about 50 years, but I have only some vague recollections of what I have read, filed away somewhere.

Here is a pic of my 500 Mbogo, on the far right of the Rogues Gallery of my own wildcats.
It sure looks a lot like the 505 Burns:



May the red gods smile upon your "500 Rigby" and mine too.

quote:

Originally posted by RIP:

I actually thought John Buhmiller beat you to the "500" on the .416 Rigby case, by about 50 years....

May the red gods smile upon your "500 Rigby" and mine too.

I sure wouldn't be surprised as there have been much smarter guys than me playing with the .416 Rigby case since what, 1911?! But if you ever find that source/reference to a .50 cal Rigby be very cool to see it.

Either way mine would be a 505 Rigby. The Mbogo a .510 Rigby RIP, what is the length of the neck on the Mbogo? Looks to be a good bit under caliber?

I know of two other .505 Burns being built now by a forum member, TJ's, son in '06. Should have been easy to do as my spec' and data were published back in 2000 on the pistolsmith.com and the Firing Line.com forums. Anyone else done something similar? How many 500 Mbogos out there?

Dane,
My 500 Mbogo neck length when fully formed to 3.000" brass is .492" neck length.
Sure is a lot better than the way short 500 Jeffery neck.
Allow me to illustrate:





A comparison of the rebated, short-necked 500 Jeffery to the 500 Mbogo perfection, all 3.000" of it: from -0.050" to +2.950" on the ruler













Shopmule 500 Mbogo No.1, it is currently getting an Ed Lapour safety installed,
by Rusty McGee, my U.K.-alumnus-mechanical-engineering-degreed gunsmith,
since the medical student gunsmith who started this 500 Mbogo is too busy right now.
This barrel was one of the last that Harry McGowen and Son made before they sent the barrel making machinery to Montana.
Dig the integral stainless dognut on the barrel, which anchors the secondary recoil lug on the bottom,
and the rear sight on top.
1:10" TWIST! :



500 Mbogo No.2 is completed but needs to be moved from the Hogback walnut to the CZ Kevlar stock, not ready for prime time yet.
I have pictures of it somewhere.
Both 500 Mbogos like this 2.5X Leupold scope setup, and BTW,
500 Mbogo No.2 has a PAC-NOR stainless barrel with 1:9" TWIST! :



I am the only RIP (Really Intelligent Person) in the world with a 500 Mbogo, 2 in fact.
It is mine, all mine. Hoooah ... and HOOO-HOOO-HOOO-HAAAA!!!

Tanzania buffalo and varmints need a taste of this!

Custom Brass by Quality Cartridge.
Custom Reloading Dies by Redding.
Chamber reamer by Manson Precision.

That is a mighty pretty piece and a hansome cartridge you have there RIP
Nice catch on the barrel twist for both.

The set back AHR trigger helped protect my 2nd knuckle on recoil if you find that an issue.

What does the rifle weight? Barrel length?

I have to think you are a really intelligent guy simply because you too obviously looked at the Jeffery and I bet said to yourself something like I did, "ya, I don't like all of that." Seems like th Mbogo could so easily be a production 50. Might happen yet, you never know.

Have fun with that Mbogo..we obviously own a set of twins sepperated at birth. I love mine and all the work that went into it.

FWIW I really like the "american" laminate stocks. Looks good on your rifle as well!

In the FYI section? My lwt 416 Taylor broke three Leopuld 1.5x5s. I have rings but don't plan of ever using a scope on my 505. Love Leopolds and they fix them every time and are extremel;y nice about. But doubt one would last 100 rds on my 505. Hell, not sure I could last 100 rds on my 505!

I recall a discussion between you and Boomstick on a thread about "age" of his 50 and the Mbogo. What was that all about if you care to enlightern me?

Also thanks for the heads up on John Buhmiller. I like the history behind what we do so I went looking for info on him.

Great post that I would like to cut and copy just to make sure it doesn't dissapear but it is too long.

Look here:

http://www.24hourcampfire.com/buhmiller.html

These are good snipits from the comments he made on his own rifles but worth reading the entire piece to get the context. No 50cal Rigby wild cats mentioned though. He liked a wildcat 505 Gibbs case with .550s and .577s..

"Elmer Keith has gone overboard on his big calibers, I think. Maybe the .460 opened up to .50 caliber would be acceptable, but I never needed anything larger than .470 caliber, and actually I found the .470 my favorite elephant caliber. It can be the Norma Special (.300 Magnum cylindrical — same as .458 caliber only a bit longer). I killed 81 elephants with that wildcat one year in a couple of months, and it was deadly. Shoulder shots, and everywhere else, except not many brain shots. The .475 A&M, which I haven't used on live animals, I'm sure would be tops. You'd be surprised how you can pile-up elephants with shoulder shots at roughly fifty yards with a .470 rifle. The .450 Magnum is almost as good.

.....more


Regarding caliber of rifles used for my shooting, I used from .416 to .505 Gibbs on the big stuff. Mostly used .450 Magnum, .460 Weatherby (the first one ever made, no doubt), and .458 Winchester. The rifle one should use depends altogether on circumstances. Much of my shooting was in very dense cover, and without an accompanying White Hunter. I liked to carry the most effective rifle I could handle, and that no doubt was the .505. If I ever go again I will take either a .50 caliber on the Weatherby case or even a .55 caliber. My friends are expecting me back in a year or two.

........then more

I have a couple of bolt actions that should see me through, or one could use a standard Mauser for a .458, but might be better to use the .470 caliber with .458 brass and 4198 powder, I shot a shell full of 4198 p0wder the other day, which is possible in the .475 bore, which has a bigger bore than the .458. I used to pour a 30-06 case full of solder (after tinning it inside) and make a 900-grain .470 bullet, but the trouble with such heavy slugs is they kick.

If someone would concentrate on that action, and simplify it all possible and keep the price down, he might make it go, where everybody else runs into costs that are too high. If we had a good strong action, one could make a rifle big enough to kill a charging buff at one or two yards distance, by using a .577 if necessary. I have killed I don't know how many at spitting distance. You blast them in the face and it seems the hunter always walks away when it is all over. I could make a two-shot or even a three-shot .577 on an Enfield action using .505 Gibbs brass (which I have done). What more would anybody need?"

Indeed, a .577 Gibbs shooting 900gr solids? What more could one need

Finally I had my first conversation with David Van Horn this morning, 7/14/10. Well known to many I suspect for his Van Horn Cartridges.
I knew of his work but everything I had seem him do was based on the belted Weatherby 460 case. 460 Weatherby came out in 1958 and is based on a .416 Rigby case with a belt added to headspace from. A-Square was better known for the 500 A-Square which is a very close duplicate of the 500 Van Horn. The A-Square 500 was first used in Africa in 1976.

I let Dave and Art argue which came first on that .50

Here are the results of the Van Horn conversation:

"I talked with David Van Horn this morning about his .50 cal Van Horn Wild cats. Most were developed 20+ years ago although he didn't pin down any specific dates when asked. But he has been building his own wild cats for 30 years, so credit does go there. The 500 Van Horn is based on the 460 Weatherby brass with a belt obviously and necked up to .510. The Van Horn 550 Magnum is indeed a .416 Rigby case blown out to a straight wall and using .510" bullets.

No question I missed Mr. Van Horn' info and his wealth of experience while designing my .505. Knowing a .510 did work I might have just used his "550 magnum". Seeems a silly name for a .510 though. Interesting Mr. Van Horn suggested the 460 weatherby case is the better choice to build on today simply for economics.

He has never done anything with the 505 and the vast majority of his designs were done early on with 460 weatherby cases. I had the feeling the .416 case was a lter development. He wouldn't verify it one way or the other when he started playing with the Rigby case but obviously didn't like it from his tone.

Might be worth a phone call if you want to know more about the family of Van Horn cartridges."

http://www.mygunroom.com/dvgunshop/vhbarrels.html

Obviously a great idea in any decade. And I applaud anyone who came to the same conclusion. But it looks like the Van Horn 550 Magnum which a number of rifles have been chambered for predates the 500Mbogo by at least 20+ years.

Hello?

Dane,
Who the heck is David Van Horn,
and what is this bizarre "550 Van Horn" shooting a 50-cal bullet?

Gil Van Horn is the master wildcatter who is in his 80's if still kicking, last sighted listening to Mozart in the desert of Kalifornistan.
500 Van Horn Express, .585 Van Horn Express, and many others ... he dates back a half century too.

Thanks for the John Buhmiller link.
Some interesting factoids.
Dr. Ken Howell knew John, wrote the article, and signed it "Th.D." ... he is a theologian of the wildcatting religion, wrote the bible of that religion.
John Buhmiller and Gil Van Horn are saints.

Member Idaho Sharpshooter also knew John Buhmiller.
Said John was working with cylindrical .416 Rigby brass in the 50's to 60's, and did something similar to the 500 Mbogo.

P.O. Ackley's book has a chapter "Africa Safari."
That is about John Buhmiller. He is quoted there recommending 105 grains of H4831 as the premier .416 Rigby load with 400-grainers. John recommended it to Jack O'Connor, and he used it to good effect too.

John Buhmiller ordered ammo from Kynoch, 18 months in advance of his safaris, .505 Gibbs, .416 Rigby, etc.

John Buhmiller did the "500 Weatherby" too, before anyone else known of.

John Buhmiller was working on a .423/.378 Weatherby in the 1960's, etc., etc.

My 500 Mbogos have 24" and 25" barrels, and a screw-on muzzlebrake adds on to the 25-incher.
Dry weight is 10 to 11 pounds, depending on the stock used.

Dave Estergaard did a 500 Mbogo Dummy in the late 1990s.
My cartridge is just that same cartridge, only allowed to grow to 3.000" max, trim to 2.990",
instead of the 470 Mbogo max brass of 2.945".